In its few months of roaming the polar area on Mars last year, the Phoenix Lander found water ice beneath the red planet’s surface and snow in the atmosphere.

While Phoenix died this past November as the winter brought on shorter and colder days, project leader Peter Smith of the University of Arizona, along with a number of colleagues from NASA’s Jet Propulsion lab and universities all over the world, have spent the intervening months confirming those early finds and poring over the lander’s massive amounts of data. Most of the attention is focused on whether Phoenix’s data conclusively shows evidence that liquid water once flowed across Mars. There is a lot of complex analysis, but, in short, signs point to yes.

Peter H. Smith, a scientist with the UA Lunar and Planetary Laboratory is the mission’s principal investigator. There are 35 co-authors from six countries on the paper. Smith and his group of scientists and students used the lander to investigate the role of water and ice on Mars, as well as the changing weather patterns.

The popular mission launched in early August 2007. In May, 2008, early 10 months later, its landing trajectory was spectacularly captured by the HiRISE camera onboard the Mars Reconnaissance Orbiter.

Over the course of the mission, Mars moved from summer to winter, and as the summer dust clouds parted, the winter clouds appeared.

“Frost was predicted, but snowfall was quite a welcome surprise,” Smith said. “In summer there was a lot of dust in the atmosphere. As we neared fall, the dust cleared, and all of a sudden there were water ice clouds forming at about 4 km (2.5 mi.) above the surface. We could see the clouds scud by, moving through the camera field, and once we saw snow coming out of the bottom of a cloud. It was very exciting to watch the daily weather changes. No one has ever had this experience.”

In some ways, it’s a cruel joke, they may get more snow on Mars than we get here in Arizona.

The notion of snow brings up an interesting proposition. Mars has an unstable spin axis, so at times in its history it have may have tilted it’s polar ice caps toward the sun, likely causing a massive snow and ice melt.

Logically one could conclude that possibly during an event like that, liquid water would exist on the planet.